Apigenin and Apigenin-7-O-β-d-Glucoside Enhance Pepper Defense Against Phytophthora capsici by Inhibiting Pathogen Growth and Reproduction

Apigenin is a natural plant flavonoid known for its remarkable biological activity. While numerous studies have documented the accumulation of glycosylated and non-glycosylated apigenin in fruits and vegetable crops, their direct and indirect effects on plant resistance remain poorly understood. This study employed non-targeted metabolomics strategies to monitor metabolome-reprogramming events in susceptible, moderately resistant, and highly resistant pepper ( Capsicum annuum) cultivars challenged with Phytophthora capsici . Results revealed a positive correlation between the accumulation of apigenin and apigenin-7-O-β-d-glucoside in pepper seedlings inoculated with P. capsici and the resistance characteristics of the individual pepper cultivars. Further, we demonstrated that both apigenin and apigenin-7-O-β-d-glucoside significantly inhibited the vegetative growth of economically important phytopathogenic oomycetes and fungi, including P. capsici , Phytophthora sojae, Pyricularia oryzae, Fusarium graminearum , and Colletotrichum siamense. These findings highlight the potential applications of glycosylated and non-glycosylated apigenin in developing biopesticides to support the environment-friendly prevention and control of critical crop fungal and oomycete diseases.